Gray leaf spot (GLS) caused by Cercospora zeae maydis is one of the major biotic constraints limiting maize (Zea mays L.) production and productivity in Kenya. The objective of this study was to evaluate inbred lines and select lines resistance to GLS from a diverse collection of genotypes and develop GLS resistant maize varieties. Forty-two diverse genotypes were evaluated for GLS resistance at two disease hotspot sites (KALRO-Kakamega and Egerton Njoro, Field 7) for two seasons in Kenya. Data on mean disease severity on leafs, area under disease progress curve (AUDPC), stalk lodging (SL), root lodging (RL), ear height (EH), ear aspect (EA), ears per plant (EPP) plant aspect (PA) and grain yield (GY) were collected. Data was subjected to analysis of variance. The genotype × environment interaction (G x E) had significant (P < 0.001) effect on all agronomic traits except RL and EPP. This is evidence of the presence of significant variation among screened inbred lines in GLS resistance across the screened sites. Maize inbred lines including CKDHL 120312, KTLN 10123, CKL 05022 and CKDHL 153502 exhibited lower values of GLS severity and AUDPC which are useful genetic resources for future GLS resistance breeding programs. Inbred lines CKDHL 153502 provided a mean grain yield of 4.3 ton/ha followed by CKDHL 120312, also (4.3 ton/ha) and CKL 05022 (4.2 ton/ha). Strong and negative correlation was found between AUDPC and GY (r = -0.65) revealing the effect of GLS. Therefore, GLS resistant and high yielding lines are ideal candidates for selection and advancement in many breeding programs.

Keywords: Inbred lines, Disease severity, GLS, Resistance, GEI and AUDPC